1Co 5:9 I wrote unto you in an epistle not to company with fornicators:
1Co 5:10 Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world.
1Co 5:11 But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat.
1Co 5:12 For what have I to do to judge them also that are without? do not ye judge them that are within?
1Co 5:13 But them that are without God judgeth. Therefore put away from among yourselves that wicked person.
There are some things that there is no middle ground on. If they are proudly homosexual, and if she says at any time that it is in any way ok she becomes a friend of this world and an enemy of God. She should not eat with them either.
If she won't take a stand for what's right, she isn't someone a Christian should be involved with. The rules she is failing to apply to them you now have to apply to her if she calls herself christian or not.